A physics-based cavitation model ranging from inertial to thermal regimes

Abstract

Cavitation in thermosensitive fluids is accompanied by a noticeable temperature drop inside a cavity. Motivated by the fact that most popular cavitation models have been developed without considering thermodynamic effects, the present study proposes physics-based corrections to existing cavitation models. Two primary corrections are adopting the physical bubble growth rate and separating bubble number density in the vaporization and condensation terms. The bubble growth rate in the cavitation model is chosen as the limiting factor between the inertia-controlled rate and heat diffusion-controlled rate from the bubble growth theories. To implement the theoretical growth rate of the thermal regime into the computational framework based on the homogeneous mixture model, the bubble time and liquid temperature are newly modeled. Furthermore, the bubble number density, which is often set uniformly throughout the whole computational domain, is separated for the vaporization and condensation processes. The vaporization bubble number density is further modeled by experimental data to reduce the empiricism inherent in the user-defined coefficients. The relation between the remaining model coefficients and characteristic temperature drop (Delta T*) is developed and it is verified to be effective in various types of fluids and working conditions. The newly proposed model is validated by cryogenic cavitating tests and applied to the computations of the 3-D cryogenic cavitating flows around a turbopump inducer. Unlike the sudden temperature recovery by the previous inertial rate-based models, the proposed model predicts a gradual temperature recovery inside a non-isothermal cavity, which is consistent with the experimental observations. It is also confirmed that the new model chooses the physical inertial rate under isothermal conditions, and thus, the model can be used regardless of the flow conditions. (c) 2021 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/)